Plant Diversity

Kingdom Plantae Multicellular eukaryotes Cell walls made of cellulose Photosynthesize using chlorophyll a and b Most are autotrophs

Early Plants and Evolution Green algae is believed to be the ancestors of the first plants – Many similarities Early plants were aquatic and are similar to today’s mosses Movement onto land meant more light, CO 2 and better soils, but plants had to avoid dessication (drying out) and needed structural support

Life Cycle Known as alternation of generations Has two alternating phases and two types of reproductive cells – Gametophyte – haploid phase that produces gametes (egg and sperm) – Sporophyte – diploid phase that produces spores Usually what we see when we look at a plant Varies among different plant groups

Gametophytes Contain “male” and “female” structures that produce the gametes – Antheridia – “male” reproductive structure that produces sperm – Archegonia – “female” reproductive structure that produces egg cells May be found on the same plant or different plants

Terms to Know Vascular – having specialized tissue to transport materials throughout plant – Xylem – transports water from roots to rest of plant – Phloem – transports nutrients and food from leaves to rest of plants Xylem and phloem make up veins

Plant Classification Divided into four main groups Based on if they have: – Vascular tissue – Seeds – Flowers Also classified by reproductive structures and body plan

Plant Cladogram

Bryophytes Nonvascular (no xylem or phloem) – Rely on osmosis No seeds Includes mosses Usually small, close to the ground, and near water (for fertilization)

Pteridophytes Vascular No Seeds Include ferns Require water for fertilization

Gymnosperms Vascular Have “naked seeds” in cones Includes conifers Have pollen grains - sperm

Angiosperms Vascular Have seeds and flowers Contain ovaries that surround and protect seeds (fruits) Includes grasses, shrubs and other flowering\fruit plants Pollen Can be grouped as monocots or dicots, woody or herbaceous, annuals, biennials, or perennials

Monocots Dicots Single cotyledon (seed leaf) Parallel leaf veins Floral parts in multiples of three Vascular bundles scattered Fibrous roots Two cotyledons Branched or net-like leaf veins Floral parts in multiples of four or five Vascular bundles in a ring Taproot (one large central root)

Angiosperm Life Cycles Annuals – complete life cycle in one growing season Biennials – complete life cycle in two years Perennials – can live for many years; often die and come back year after year

Advantages of Seed Plants (Gymnosperms and angiosperms) Seeds – embryo and food supply encased in a protective coat Seed dispersal – wind (wings and propellers), animals (fruits eaten and digested or burrs that stick to fur) Pollen and pollination – eliminates need for water for fertilization and dispersed in many ways Gametophyte structures and seeds held in cones or flowers